The marine mammals of Península Valdés

Although diverse and significant populations of birds and terrestrial mammals exist on Península Valdés, it is the marine mammals here that are of particular interest.

Southern right whale

The southern right whale (Ballena franca austral) comes to the sheltered waters of the Golfo Nuevo and Golfo San José to breed. Weighing up to fifty tonnes and measuring up to 18m in length, these gentle leviathans are filter-feeders, deriving nutrients from plankton. Once favoured targets for the world’s whalers – they were the “right” whales to harpoon, as they were slow, yielded copious quantities of oil and floated when killed – they have now been declared a “National Natural Monument”, and are protected within Argentine territorial waters. This has enabled the present tourist industry to develop, reinforcing the economic value of keeping these creatures alive; their charming curiosity – a trait that once put them in danger – now makes them one of the most enjoyable cetaceans to view in the wild.

Killer whales

The killer whale, or orca, is not in fact a whale at all, but the largest member of the dolphin family – it displays the high levels of intelligence we associate with such creatures, if not their cuteness. This is amply demonstrated in their unique hunting behaviour at Caleta Valdés and Punta Norte, where orcas storm the shingle banks, beaching themselves in order to snap up their preferred prey: baby sea lions and young elephant seals. Male killer whales have been known to measure over nine metres, and weigh some eight tonnes, although the ones off Valdés do not reach these sizes. The dorsal fin on an adult male is the biggest in the animal kingdom, measuring 1.8m, and its size and shape is one of the factors used to identify individual orcas, along with the shape of the saddle patch and colour variations. If you want to know more, contact Fundación Orca in Puerto Madryn (t0280 445 4723, wfundorca.org.ar).

Sea lions

Sea lions (Lobos marinos) were once so numerous on the peninsula that 20,000 would be culled annually for their skins and blubber – a figure that roughly equals the entire population found here today. They are the most widely distributed of the Patagonian marine mammals and their anthropomorphic antics make them a delight to watch. It’s easy to see the derivation of the name when you look at a 300kg adult male, ennobled by a fine yellowy-brown mane.

Elephant seals

Península Valdés is the only continental breeding ground for the southern elephant seal (Elefante marino). Weighing some three tonnes and measuring four to five metres, bull elephant seals mean business. Though the average size of a harem for a dominant male ranges between ten and fifteen females, some super-stud tyrants get greedy. One macho male at Caleta Valdés infamously amassed 131 consorts. October is the best month to see these noisy clashes of the titans, but be prepared for some gore, as tusk wounds are inevitable. Adult females, much smaller than the males, are pregnant for 11 months of the year, giving birth from about mid-September. Pups weigh 40kg at birth, but then balloon to weigh 200kg after only three weeks. The elephant seal’s most remarkable attribute, however, is as the world’s champion deep-sea-diving mammal. Depths of over 1000m are not uncommon, and it is reckoned that some of these animals have reached depths of 1500m, staying submerged for a (literally) breathtaking two hours.